There are usually many different sizes, from 25mm up to 50mm even ones that both go up and back, so far no one I have supplied has ever needed to extend the brakelines etc, there is usually enough spare in them.
I fitted a set of the "up and back" risers when I changed the bars for Renthals. (I am only a short-arse and prefer sat up to leaning forward) The only change to the controls and cables that I made was to the throttle cable routing, and that was more to do with my tank bag mounts fouling than anything else. My throttle cable now runs to the front of the bars, as opposed to the rear. Brake hose needed no alteration. Really must get my camera back to post pics!
HTH
Mark
Got some (35mm I think?) and they've made a big difference. I'm 6'2" so used to lean forward slightly more than I liked. I was getting the tennis elbow effects - but now cured.
Cable re-routing was easy once it was explained by another good member of this site and apart from removing the bolts at the top of the fork sliders and moving the cables, no parts are needed.
I also (inadvertent amnesia moment) ordered the Wunderlich risers. I haven't tried them yet but once I have I'll post a report - and put one set up for sale!!